package leetcode;

import java.util.HashMap;
import java.util.Map;

public class LeetCode13 {

    public int romanToInt1(String s) {
        int result = 0;
        Map<Character, Integer> dict = new HashMap<>();
        dict.put('I', 1);
        dict.put('V', 5);
        dict.put('X', 10);
        dict.put('L', 50);
        dict.put('C', 100);
        dict.put('D', 500);
        dict.put('M', 1000);

        for (int i = 0; i < s.length() - 1; i++) {
            Integer integer = dict.get(s.charAt(i));
            if (integer >= dict.get(s.charAt(i + 1))) {
                result += integer;
            } else {
                result -= integer;
            }
        }
        return result + dict.get(s.charAt(s.length() - 1));
    }
//------------------------------------------------------------------

//    可以使用switch代替hashmap

    public int romanToInt(String s) {
        int sum = 0;
        int preNum = getValue(s.charAt(0));
        for(int i = 1;i < s.length(); i ++) {
            int num = getValue(s.charAt(i));
            if(preNum < num) {
                sum -= preNum;
            } else {
                sum += preNum;
            }
            preNum = num;
        }
        sum += preNum;
        return sum;
    }

    private int getValue(char ch) {
        switch(ch) {
            case 'I': return 1;
            case 'V': return 5;
            case 'X': return 10;
            case 'L': return 50;
            case 'C': return 100;
            case 'D': return 500;
            case 'M': return 1000;
            default: return 0;
        }
    }
}
